In a VA-mode or OCB-mode liquid crystal cell, liquid crystal molecules are aligned in a vertical direction without the application of a voltage. Therefore, when the liquid crystal panel is seen in an oblique direction, the liquid crystal molecules are apparently aligned in an oblique direction, and the polarization state of light from the oblique direction changes due to the birefringence of liquid crystal, which generates light leakage from polarizing plates. Further, the polarizing plates block light by being laminated so that absorption axes thereof are perpendicular to each other. When the polarizing plates in such a laminated state are seen from the oblique direction, the absorption axes of the polarizing plates are apparently non-perpendicular state, which generates light leakage from the polarizing plates.
In order to solve the above-mentioned problem, techniques are disclosed, which compensate for the influence on light leakage caused by the birefringence of liquid crystal and the axis displacement of the polarizing plates by using biaxial optical compensation plates having a relationship: nx>ny>nz (nx represents a refractive index in a slow axis direction, ny represents a refractive index in a fast axis direction, and nz represents a refractive index in a thickness direction) (e.g. see Patent Documents 1 to 5). However, these techniques are insufficient in the enhancement of a screen contrast, the reduction of a color shift, and the suppression of display unevenness.
[Patent Document 1] Japanese Patent Application No. 2003-000926
[Patent Document 2] Japanese Patent Application No. 2003-027488
[Patent Document 3] Japanese Patent Application No. 2003-038734
[Patent Document 4] Japanese Patent Application No. 2002-063796
[Patent Document 5] Japanese Patent Application No. 2002-222830